2. UV Radiation 1.UV light causes chemical changes to bases…. HOW? This prevents DNA from replication properly 2.Prevent damaged DNA from passing on information. What ‘systems’? 3.Skin covers the entire body and is directly exposed to sun 4.Mutations in their DNA repair systems (passed down from parents) prevent repair

3. UV Radiation UV light contains more energy than white light DNA can absorb this energy What happens to electrons? Electrons ‘bounce around’

6. UV Radiation Thymine dimers What factors would determine how well you can get rid of these dimers = mutations?

7. Tautomers Bad things happen to Good Bases

8. What is deamination? deAMINation? What happens when cytosine get deaminated? What would the consequences be?

9. Deamination Cytosine

10. Deamination Cytosine just add water… and heat H2OH2O NH3

11. Deamination Cytosine

12. Deamination Cytosine Hmmm, this is ALMOST IDENTICAL to THIS Mutated Cytosine Thymine

13. DNA Mutations So, if all you need to mutate DNA is heat and water and/or oxygen… And you’re 50-60% water and pretty warm… Why isn’t your DNA mutated beyond recognition? Figure 12.7 ‘gives’ you the answer

14. Deamination Cytosine Mutated Cytosine Thymine

15. DNA Mutations What’s the real benefit to double-stranded DNA? The two strands PROTECT each other from water!!! Also, make it easy to copy and proofread!!!

17. DNA Replication Eukaryote vs Prokaryote Venn diagram comparing the two Include: Where it occurs, where it begins, how it proceeds/goes, form of the DNA, enzymes that puts new strands together, etc.

18. Homework Pages 356 - 358, 9-15, 18-24, 32-34 Due MONDAY!